We know pigs have, but that's because apparently, even in the 41st millenia, pig skin makes for the best writing medium.

But the serious answer would be that grox represents a cheaper or easier livestock to raise displacing beef, chicken, and / or mutton/lamb. Perhaps to such an extent that galactically that they have become exotic. A parallel to this IRL is organ meat, at least in the US. A century ago, things like tongue, tripe, or pigs' ears were pretty common. Now you might find them at a supermarket but will likely have to go a kinda boutique-y niche store to get it.